Compressed Air Cartridge

ABSTRACT

A compressed gas cartridge is provided that includes a hollow cartridge front section having a male high-pressure gas quick-connect fitting, a forward piston-receiving channel, and a projectile receptacle; a hollow cartridge rear section having a rear piston-receiving channel and a forward valve seat; a center cylinder connected between the cartridge front and rear sections and including an interior gas storage space; and a piston that sealably fits within the front and rear piston-receiving channels. The piston has a solid rearward portion configured with a striking surface and a hollow forward portion. The hollow forward portion has an exterior cylindrical, concentric seal with a rearward edge configured to sealably engage the valve seat. Piston exhaust/fill holes just rearward of the concentric seal allow compressed gas to move between the gas storage space and the hollow interior of the piston forward portion during both discharge and filling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This nonprovisional application claims the benefit of co-pending U.S. Provisional Patent Application Ser. No. 61/844,737, filed on Jul. 10, 2013, which is incorporated herein in its entirety.

FIELD OF INVENTION

This invention relates generally to a self-contained compressed gas cartridge.

BACKGROUND OF THE INVENTION

Compressed gas cartridges may power ammunition for small arms. Additionally, compressed gas cartridges can provide a power source for other applications, such as to power a nail gun, impact wrenches or other small tool actuators.

Basic air cartridge designs date back well over a hundred years. However, previous designs have numerous disadvantages. These include: (1.) the complication of numerous small parts; (2.) the need to dismantle a cartridge to fill it and then to reassemble it prior to use; (3.) the requirement for specialized pumps, often hand pumps, to fill the cartridges; (4.) the limitation to low gas volumes and/or to low pressures realized due to the filling methods employed and due to the complicated internal mechanisms of the cartridges; (5.) the length of time and difficulty in filling the air cartridges; and (6.) the relatively low power output of the conventional cartridge, for example, causing a lower muzzle velocity of the exiting projectile. For instance, with conventional cartridge designs, the kinetic energy output of the air cartridge is around 16 joules (12 ft/lbs).

There is a need for a compressed gas cartridge that is more robust with fewer complicated parts; does not need to be dismantled to fill and reassembled to use; does not require specialized pumps for refilling; is not limited to the low gas volumes and/or pressures of conventional cartridges; is quick and easy to refill; and has an increased power output.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to a compressed gas cartridge that is described to operate in purpose-built small arms (such as pistons, rifles and automatic small arms or other gun-type devices) to launch projectiles at high velocities, but that may also be used as a power source for other applications.

The compressed gas cartridge includes a hollow front cartridge section, a hollow rear cartridge section, a center cylinder connected between the hollow front cartridge section and the hollow rear cartridge section, and a piston assembly.

The hollow front cartridge section has an interior forward piston-receiving channel and an exterior male high-pressure quick-connect fitting. The quick-connect fitting allows rapid connection of the cartridge to a corresponding female quick-connect fitting on a standard compressed gas source, such as a scuba tank or gas compressor, for fast and convenient filling of the cartridge.

The hollow rear cartridge section has a forward female valve seat and an interior rear piston-receiving channel.

The center cylinder includes an interior surface partly defining the gas storage space, which is also defined by inner surfaces of the hollow rear cartridge section and the hollow front cartridge section.

The piston assembly includes a spring and a piston. The piston extends from the forward piston-receiving channel through the interior gas storage space and into the rear piston-receiving channel. The piston has a hollow forward piston portion and a solid rear piston portion. The rear cartridge posterior portion of the hollow forward portion has an exterior cylindrical, concentric seal with a male rearward edge configured to sealably engage with the female valve seat. At least the outer rearward edge of the concentric seal is formed of a polymer, preferably the acetal copolymer Delrin®. The piston also has exhaust/fill holes just rearward of the concentric seal that allow compressed gas to move between the gas storage space and the hollow interior of the piston forward portion during both discharge and filling.

An object of the present invention is to provide a compressed gas cartridge that is quick and easy to fill.

An additional object of the present invention is to provide a compressed gas cartridge that does not need to be dismantled to fill and reassembled to use.

A further object of the present invention is to provide a compressed gas cartridge that does not require specialized pumps for refilling.

Another object of the present invention is to provide a compressed gas cartridge that has an increased power output compared to some conventional compressed air cartridges.

These and other objects, features and advantages of the present invention will become more readily apparent from the attached drawings and from the detailed description of the preferred embodiments which follow.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the invention, where like designations denote like elements.

FIG. 1 is a front perspective view of an embodiment of the gas cartridge of the present invention.

FIG. 2 is an exploded perspective view of an embodiment of the gas cartridge of the present invention.

FIG. 3 is a top view of an embodiment of the gas cartridge of the present invention shown with a projectile to be used with the gas cartridge.

FIG. 4 is a cut view with the frontward half of the exterior of the gas cartridge removed to allowing viewing of the interior components.

FIG. 5 is a perspective view of an embodiment of the gas cartridge of the present invention in an exemplary filling environment.

Like reference numerals refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

Shown throughout the figures, the present invention is directed toward a compressed gas cartridge that, compared to conventional cartridges, removes the need to dismantle and reassemble the cartridge during filling, attaches to standard compressed air sources, fills more quickly, reduces the number and complexity of interior parts leading to a more robust design, and increases the power output significantly. Though the compressed gas cartridge is described herein for use with purpose-built small arms (such as pistons, rifles and automatic small arms or other gun-type devices) to launch projectiles at high velocities, it may also be used as a power source for other applications.

Referring now to FIG. 1, a compressed gas cartridge, shown generally as reference number 10, is illustrated in accordance with a preferred embodiment of the present invention. As shown, the compressed gas cartridge 10 includes a hollow rear cartridge section 20, a hollow front cartridge section 40, a center cylinder 30 connected between the front cartridge section 40 and the rear cartridge section 20, and a piston assembly 60 (FIG. 2).

The hollow front cartridge section 40 has a front cartridge anterior portion and a front cartridge posterior portion. The front cartridge anterior portion is configured with an exterior male high-pressure quick-connect fitting 45 that allows rapid connection of the cartridge 10 to a corresponding female quick-connect fitting on a conventional high-pressure compressed gas source, such as a compressed gas reservoir 70 (FIG. 5) or gas compressor. The inventive cartridge allows for compressed gas to be filled at pressures between 100 BAR and 300 BAR (1450 psi to 4,350 psi), typically operating at the 200-250 BAR range (2900 psi-3,625 psi), which is a typical pressure for the diving cylinders that are envisaged to be the key source of compressed air/gas. Higher pressure gas sources are available, as are compressors easily capable of reaching pressures higher than 300 BAR.

The front cartridge anterior portion of hollow front cartridge section 40 also includes a projectile receptacle 42 (FIG. 4) defined by the inner surface of the forward end 41 of the hollow front cartridge section 40. The projectile receptacle 42 will accept a bullet, pellet or other projectile 15 (FIG. 3) of the chosen designation or caliber. The projectile receptacle 42 is a machined hole of dimensions appropriate to the pre-selected caliber. The caliber of the air cartridge is designated by the size and diameter of the hole in the forward end 41 of the hollow front cartridge section 40 and is designed to operate in calibers from .22 to .50. For example, in the .357 caliber air cartridge the forward end 41 is machined to accept a projectile 9.1 mm in diameter×10 mm in length. However, longer (or shorter) projectiles 15 (FIG. 3) may be inserted as the forward end 41 is of open design. Testing has shown that the inventive air cartridge can be designed for a wide range of currently available commercial ammunition and commercially accepted calibers. The inventive air cartridges have been tested with bullets having up to a diameter of .358″ (9.1 mm), having up to a length of 0.75″ (19 mm), and weighing up to 200 grains.

As seen in FIG. 4, the front cartridge posterior portion of hollow front cartridge section 40 has an interior forward piston-receiving channel 44 defined by channel edges 48. The forward piston-receiving channel 44 is a cylindrical channel, the back portion of which, at least, has a diameter sufficient to accommodate the diameter of the front portion of piston 65.

The hollow rear cartridge section 20 has a rear cartridge anterior portion and a rear cartridge posterior portion. A forward valve seat 21 is machined into the rear cartridge anterior portion. The exterior of the rear cartridge posterior portion may include a locator fitting 25 configured to relate to a corresponding fitting within the gun-type device.

The interior surface of the rear cartridge posterior portion forms an interior rear piston-receiving channel 22. The rear piston-receiving channel 22 is a cylindrical channel that has a diameter sufficient to accommodate the diameter of the rear portion of piston 65. The interior surface 28 of the rear cartridge anterior portion forms a rear valve channel 19 extending from in front of sealing device 57 and forward to the forward edge of the forward valve seat 12.

The center cylinder 30 is connectable to the hollow rear cartridge section 20 and the hollow front cartridge section 40. In a preferred aspect, the center cylinder 30 is removably connectable. Shoulders 49 of the hollow front cartridge section 40 and the hollow rear cartridge section 20 may extend outwardly to meet and to form a smooth exterior with the exterior surface of cylinder wall 39. As shown, the center cylinder 30 is configured with front female threads 36 and rear female threads 34 that correspond to front male threads 46 disposed on the exterior surface of the front cartridge posterior portion of hollow front cartridge section 40 and to the rear male threads 24 disposed on the exterior surface of the rear cartridge anterior portion of the hollow rear cartridge section 20, respectively. In this aspect, sealing devices, such as O-rings, prevent compressed gas from leaking at the threaded areas. A front external sealing device 37 is disposed on the exterior of the posterior portion of hollow front cartridge section 40, and a rear exterior sealing device 27 is disposed on the exterior surface of said hollow rear cartridge section 20. Alternatively, the front or rear portion of the center cylinder 30 may be permanently attached to the hollow front cartridge section 40 or hollow rear cartridge section 20. The center cylinder 30 is preferably a high-grade pressure-resistant metal tube.

The cylinder inner surface 18 of the cylinder wall 39 of center cylinder 30 defines the lateral cylindrical outer edges of an interior gas storage space 14. The remainder of the gas storage space 14 is defined by forward portions of the hollow rear cartridge section 20 and rearward portions of the hollow front cartridge section 40, as seen in FIG. 4.

The piston assembly 60 includes a spring 35 and a piston 65. The piston 65 extends from a front edge 53 of a hollow forward piston portion 54 received by the forward piston-receiving channel 44 through the interior gas storage space 14 and into the rear piston-receiving channel 22 ending at solid end actuating surface 58 of solid rear piston portion 52. The piston 65 has a hollow forward piston portion 54 configured to sealably fit within at least a portion of the forward piston-receiving channel 44 and has a solid rear piston portion 52 configured to sealably fit within at least a portion of the rear piston-receiving channel 22. A front internal sealing device 47 seals between the hollow forward piston portion 54 and the forward piston-receiving channel 44. A rear internal sealing device 57 seals between the solid rear piston portion 52 and the rear piston-receiving channel 22. The forward piston portion 54 is hollow from front edge 53 to the forward surface 61 of solid rear piston portion 52.

The hollow forward piston portion 54 is configured with a rearwardly disposed polymer seal assembly 50. The seal assembly 50 includes an exterior cylindrical, concentric seal 55 with an outer rearward edge 51 configured to sealably engage with the valve seat 21. The sealable edge of concentric seal 55 is preferably formed of an acetal copolymer, such as a polymer that has high tensile strength, stiffness, creep resistance and impact resistance, and that has good high-temperature performance and good mating with metal. In one preferred aspect, the acetal copolymer is DuPont™ Delrin®. The polymer concentric seal 55 may be attached to the piston 65 in any manner as known in the art. In one aspect, the concentric seal 55 may be attached directly to the piston 65 with an adhesive such as epoxy resin. In another aspect the seal 55 may be threaded onto and permanently affixed to a metal support 56 that is machined into the hollow forward piston portion 54 of piston 65.

A spring seat 59 may be attached to, integrated into or formed unitarily with the forward-facing surface of the concentric seal 55. Spring 35 is disposed around the hollow forward piston portion 54 and extends from the spring seat 59 to the posterior portion of the hollow front cartridge section 40.

At the rearward end of hollow forward piston portion 54 of piston 65 there is at least one exhaust/fill hole 33 defined by exhaust/fill hole edges 32. In the preferred aspect, the exhaust/fill hole edges 32 define a single exhaust/fill hole 33 extending through the rearward end of the hollow forward piston portion 54. The exhaust/fill hole 33 is just rearward of the outer rearward edge 51 of concentric seal 55. The at least one exhaust/fill hole 33 allows compressed gas to move between the gas storage space 14 and the hollow interior of the piston forward portion 54 during both discharge and filling of the air cartridge.

In an aspect, the hollow front cartridge section 40 includes a check valve 31 disposed at the rearward end of the front cartridge posterior portion of the hollow front cartridge section 40. An inner surface of the check valve 31 forms a rearward portion of the forward piston-receiving channel 44. The check valve 31 is configured to move rearward during the inflow of compressed air during the filling procedure, providing another pathway by which the high pressure compressed air may proceed into the interior gas storage space 14. Preferably the check valve 31 is formed of a brass material. Preferably the hollow front cartridge section 40 further includes a check valve/posterior sealing device 43, such as an O-ring, disposed between the check valve and the front cartridge posterior portion.

To fill the cartridge 10, the exterior male high-pressure quick-connect fitting 45 is coupled to a corresponding female quick-connect fitting 75 (FIG. 5) on a conventional high-pressure compressed gas source 70, and a gas-source valve 73 is opened. The compressed gas moves from the gas source 70 through the male high-pressure quick-connect fitting 45 at the front cartridge anterior portion of the hollow front cartridge section 40 (FIG. 4), then through the forward piston-receiving channel 44 at the posterior portion of the hollow front cartridge section 40, and past the hollow piston front end 53 into the hollow forward piston portion 54. The compressed gas exits the hollow forward piston portion 54 through at least one exhaust/fill hole 33 into the rear valve channel 19 formed by the interior surface 28 of the rear cartridge anterior portion and pushes against the back surface of the concentric seal 55, forcing the concentric seal outer rearward edge 51 to separate from the valve seat 21 to create a seal valve gas passage allowing the compressed gas to rush into the gas storage space 14. The gas-source valve 73 (FIG. 5) is then closed to prevent further flow of compressed gas out of the compressed gas source 70, excess gas is vented through bleed-off valve 71, and the cartridge 10 is released from the gas source 70 by disengaging the male high-pressure quick-connect fitting 45 from the corresponding female fitting. The entire filling procedure can typically be performed in under five seconds.

The cartridge 10 is introduced into a power-controlling device, such as a weapon, nail gun, impact wrench or the like. In the typical application in which the cartridge 10 is being used in a weapon, a projectile 15 (FIG. 3) of the chosen caliber is manually inserted into the projectile receptacle 42 (FIG. 4) by pushing. The cartridge 10 is then manually placed into the weapon.

An actuating force (for example, a strike of suitable force, akin to the strike from a firing pin) is applied to the end actuating surface 58. This actuating force causes the piston 65 to move forward, unseating the concentric seal outer rearward edge 51 from the valve seat 21 and causing them to separate to create a seal valve gas passage, which allows the compressed gas to rush from the gas storage space 14 through the at least one exhaust/fill hole 33 and into the hollow forward piston portion 54 to reach the base of projectile 15 (FIG. 3) and to explosively accelerate the projectile 15 out of the cartridge 10, and then out of the weapon barrel. The gas passing at high pressure along the inside of the hollow forward piston portion 54 propels the projectile at a high rate of velocity. While historical kinetic energy output of conventional air cartridges is around 16 joules (12 ft/lbs), the inventive cartridge 10, when fired through the correct platform, demonstrates muzzle kinetic energies in the range of 100-300 joules (75 ft/lbs to over 220 ft/lbs) depending on type of fill gas and pressure used.

After the explosive discharge of the compressed gas during the firing sequence, the spring 35 around the hollow forward piston portion 54 pushes the concentric seal 55 against the valve seat 21 in a ready position for filling of the cartridge 10, as shown in the position of the piston 65 of FIG. 4. No dismantling is required to fill or use.

In the aspect which includes the check valve 31, during the filling procedure the compressed gas from the high-pressure gas source 70 (FIG. 5) may force the check valve 31 backward to unseat the check valve/posterior sealing device 43 and to open a check valve gas passage between the outside edges of the check valve 31 and the interior surface of the front cartridge posterior portion of the hollow front cartridge section 40. Compressed gas is forced through the check valve gas passage into the gas storage space 14.

Preferably the hollow rear cartridge section 20, hollow front cartridge section 40, center cylinder 30 and piston 65 are formed using a high-grade pressure-resistant metal.

The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein.

Since many modifications, variations, and changes in detail can be made to the described preferred embodiments of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents. 

What is claimed is:
 1. A cartridge, comprising: a hollow front cartridge section having a front cartridge anterior portion and front cartridge posterior portion comprising: a male high-pressure gas quick-connect fitting disposed at said front cartridge anterior portion; a forward piston-receiving channel formed within said front cartridge posterior portion; a hollow rear cartridge section having a rear cartridge anterior portion and a rear cartridge posterior portion comprising: a rear piston-receiving channel defined by at least a portion of the interior surface of said rear cartridge posterior portion; a rear valve channel defined by at least a portion of the interior surface of said rear cartridge anterior portion; a female valve seat disposed on the forward portion of said rear valve channel; a center cylinder connectable between said front cartridge posterior portion and said rear cartridge anterior portion, said center cylinder comprising a cylinder inner surface defining a portion of an interior gas storage space; and a piston assembly comprising: a piston shaft comprising a hollow forward piston portion and a solid rearward piston portion; wherein said hollow forward piston portion is configured to sealably fit within at least a portion of said forward piston-receiving channel; wherein said hollow forward piston portion comprises at least one exhaust/fill hole edge defining a least one exhaust/fill hole between the hollow interior and the exterior of said hollow forward piston portion; wherein said solid rearward piston portion is configured to sealably fit within at least a portion of said rearward piston-receiving channel; wherein said solid rearward piston portion comprises an end actuating surface; an exterior cylindrical, concentric seal attached at a rearward portion of said hollow forward piston portion, said concentric seal comprising a seal outer rearward edge configured to sealably engage said valve seat; wherein said at least one exhaust/fill hole edge is disposed rearward of said rearward edge of said concentric seal and forward of said rear interior sealing device; and a spring extending between said concentric seal and the rearward end of said front cartridge posterior portion.
 2. The cartridge, as recited in claim 1, wherein said hollow front cartridge section further comprises a check valve disposed at the rearward end of said front cartridge posterior portion, wherein said check valve has an interior portion comprising a portion of said forward piston-receiving channel.
 3. The cartridge, as recited in claim 2, wherein said check valve is formed of a brass material.
 4. The cartridge, as recited in claim 2, wherein said hollow front cartridge section further comprises a check valve/posterior sealing device disposed between said check valve and said front cartridge posterior portion.
 5. The cartridge, as recited in claim 1, wherein at least a portion of said concentric seal including at least said seal outer rearward edge is formed of an acetal copolymer.
 6. The cartridge, as recited in claim 5, wherein said acetal copolymer comprises DuPont™ Delrin®.
 7. The cartridge, as recited in claim 1, wherein: said front cartridge posterior portion is configured with male threads; said rear cartridge anterior portion is configured with male threads; said center cylinder comprises a cylinder anterior portion and a cylinder posterior portion; said cylinder anterior portion is configured with female threads corresponding to said male threads of said front cartridge posterior portion; and said cylinder posterior portion is configured with female threads corresponding to said male threads of said rear cartridge anterior portion.
 8. The cartridge, as recited in claim 1, wherein said front cartridge anterior portion comprises inner walls defining a projectile receptacle configured to receive a projectile.
 9. The cartridge, as recited in claim 1, further comprising: a front external sealing device on the exterior of said front cartridge posterior portion for sealing between said front cartridge posterior portion and said center cylinder; a rear external sealing device on the exterior of said rear cartridge for sealing between said rear cartridge and said center cylinder; a front internal sealing device disposed on the surface of said forward piston-receiving channel; and a rear interior sealing device disposed on the interior surface of said rear piston-receiving channel.
 10. A method of using compressed gas to provide a power source, comprising: providing a compressed gas filled cartridge comprising a hollow cartridge front section, a center cylinder comprising an inner surface defining an interior gas storage space, a hollow cartridge rear section, and a piston assembly including a piston and a spring; wherein said hollow rear cartridge section comprises a valve seat; wherein said piston assembly comprises a hollow forward piston portion, a solid rearward piston portion comprising an end actuating surface, an exterior cylindrical concentric seal having a seal outer rearward edge configured to seal against said valve seat, and at least one exhaust/fill hole edge defining at least one exhaust/fill hole disposed in said hollow forward piston portion rearward of a plane formed by said seal outer rearward edge; inserting said cartridge in a power-controlling device; actuating an actuator against said end actuating surface; causing said piston to move forward within said cartridge; causing said seal outer rearward edge to break its seal with said valve seat; and allowing said compressed gas to explosively move from said gas storage space through said at least one exhaust/fill hole and through the interior of said hollow forward piston portion to exit out the front of said hollow cartridge front section.
 11. The method as recited in claim 10, wherein at least a portion of said concentric seal including at least said seal outer rearward edge is formed of an acetal copolymer.
 12. The method as recited in claim 10 further comprising: attaching a cartridge configured with a male quick-connect fitting disposed on said hollow cartridge front section to a corresponding female quick-connect fitting on a compressed gas source; opening a gas-source valve on said compressed gas source to allow compressed gas to flow through said female quick-connect fitting and said male quick-connect fitting; forcing compressed gas into said gas storage space; wherein said forcing compressed gas into said gas storage space comprises forcing apart said concentric seal outer rearward edge from said valve seat to create a seal valve gas passage, and forcing compressed gas through said seal valve gas passage into said gas storage space; closing said gas-source valve on said compressed gas source to prevent further flow of compressed gas out of said compressed gas source; and releasing said male quick-connect fitting from said corresponding female quick-connect fitting.
 13. The method as recited in claim 12 wherein said forcing compressed gas into said gas storage space further comprises forcing backward a check valve disposed in said hollow cartridge front section to open a check valve gas passage and forcing compressed gas through said check valve gas passage into said gas storage space.
 14. The method as recited in claim 10 wherein said power-controlling device comprises a gun-type device.
 15. A method of using compressed gas to provide a power source, comprising: attaching a cartridge configured with a male quick-connect fitting to a corresponding female quick-connect fitting on a compressed gas source; wherein said cartridge comprises a hollow cartridge front section comprising said male quick-connect fitting, a center cylinder comprising a gas storage space, a hollow cartridge rear section, and a piston assembly comprising a piston and a spring; wherein said hollow rear cartridge section comprises a valve seat; wherein said piston comprises a hollow forward piston portion, a solid rearward piston portion comprising an end actuating surface, an exterior cylindrical concentric seal having a seal outer rearward edge configured to seal against said valve seat, and at least one exhaust/fill hole edge defining at least one exhaust/fill hole disposed in said hollow forward piston portion rearward of a plane formed by said seal outer rearward edge; opening a gas-source valve on said compressed gas source to allow compressed gas to flow through said female quick-connect fitting and said male quick-connect fitting; forcing compressed gas into said gas storage space; wherein said forcing compressed gas into said gas storage space comprises forcing apart said concentric seal outer rearward edge from said valve seat to create a seal valve gas passage, and forcing compressed gas through said seal valve gas passage into said gas storage space; closing said gas-source valve on said compressed gas source to prevent further flow of compressed gas out of said compressed gas source; and releasing said male quick-connect fitting from said corresponding female quick-connect fitting.
 16. The method as recited in claim 15 wherein said forcing compressed gas into said gas storage space further comprises forcing backward a check valve disposed in said hollow cartridge front section to open a check valve gas passage and forcing compressed gas through said check valve gas passage into said gas storage space.
 17. The method as recited in claim 15, wherein at least a portion of said concentric seal including at least said seal outer rearward edge is formed of an acetal copolymer.
 18. The method as recited in claim 15 further comprising: inserting said cartridge filled with compressed gas into a power-controlling device; actuating an actuator against said end actuating surface; causing said piston to move forward; causing said seal outer rearward edge to break its seal with said valve seat; and allowing said compressed gas to explosively move from said gas storage space through said at least one exhaust/fill hole and through the interior of said hollow forward piston portion to exit out the front of said hollow cartridge front section.
 19. The method as recited in claim 15 wherein said power-controlling device comprises a gun-type device. 